Originally Posted by evilghost
Manual SMTP interaction: telnet [host] 25
Manual HTTP interaction: telnet [host] 80
Manual IMAP/POP interaction: telnet [host] 143/110
Basic port discovery (without need for netcat): telnet [host] [dport]
Many people dont' use telnet.exe only for telnet, to assume so is obtuse.
Why would you do any of these with an ordinary telnet client? There are much better tools for these.